Cooling of machine guns



Feb. 7, 1939. P. F. ROSSMANN 2,146,554

' I COOLING OF MACHINE GUNS Filed Nov. 5, 1937 INVENTOR PETER F.RoasMANN.

ATTORNEY Patented Feb. 7, 1939 UNITED STATES COOLING OF MACHINE GUNSPeter F. Rossmann, Kenmore, N. Y., assignor to Curtiss-WrightCorporation, a corporation of Delaware Application November 3, 1937,Serial No. 172,540

3 Claims.

This invention relates to cooling of machine guns, and particularly tomeans by which aircraft machine guns subject to rapid and continuousfire may be maintained at safe operating 3 temperatures.

In the prior art, air cooling andwater cooling have been resorted to formachine guns, and this invention has for an object the provision ofcooling by the use of refrigerants or comltl pressed gases. Theinvention is particularly adapted for use with machine guns used onaircraft, and the need for a cooling system of this kind may bevisualized by the following: Military aircraft have ordinarily beenequipped with 13 two fixed machine guns, and the practical use of theguns contemplated interrupted fire which permitted the guns to coolbetween bursts. Now, requirements are that the aircraft be capable ofalmost continuous gun fire, and proposals to 20 attain this end haveincluded the use of a much greater number of guns, so that alternate usemay be made of the guns to maintain a continuity of total fire, whilepermitting certain of the guns to stand by for cooling. The increased 25number of guns adds weight and control complication to the aircraft.Accordingly, I propose the use of refrigerating substances for thecooling of only a few guns on the aircraft, so that these guns may beused almost continuously 30 without overheating.

Further objects will be apparent from a-reading of the annexedspecification together with an examination of the accompanying drawing,in which:

35 Fig. 1 is a side elevation of a machine gun equipped with the coolingtube of the invention;

Fig.2 is a longitudinal section of the cooling tube as applied to a gun;

Figs. 3 and 4 are sections, respectively, on the 40 lines 3-3 and 4-4 ofFig. 2;

Fig. 5 is a longitudinal section through analternative form of coolingdevice, as applied to a gun; and

Fig. 6 is a section on the line 6-6 of Fig. 5. 45 In the drawing, theconventional type of machine gun'is shown at Ill, the barrel ll of thegun being embraced, as shown in Figs. 1 to 4, by a double-walleddetachable cooling device I2, the .outer wall thereof being imperforate,and the 50 inner wall l3 being perforate as at It. The inner wall is ofsuch a size at its rearward end as to fit snugly over the breach end ofthe barrel H, while indentations 15 are formed in the forward end of thewall I3 to engage, at spaced i5 apart points, the periphery of theforward end of the barrel. The space between the walls l2 and I3 isfilled with CO2 snow, commonly known as dry ice which, as is well known,has a very effective refrigerating effect. The perforations I l, and thespace between the indentations l5 5 provides for evaporation of the CO2whereby the cooling effect is obtained. In use, it is contemplated thata plurality of the units l2 be available at ground stations, and thatprior to takeoff, the machine guns of the aircraft be fitted 10 withfreshly filled cooling assemblies. During flight, the cooling tubes willhave a constant cooling and refrigerating effect upon the gun barrel toprevent overheating thereof during firing. The rate of evaporation ofdry ice is sufficiently low, so that a single cooling device l2 willlast for an adequate period of time.

An alternative arrangement for cooling the gun is shown in Figs. 5 and6, wherein a tube I6 is flanged at its ends to closely engage the breechand muzzle ends of the barrel H. Perforations I! are formed toward thebreech end of the tube I 6, to permit of outflow of gas fed within thetube, and a connection I8 is provided at the muzzle end, to which apressure bottle I9, having a valve 20, is attached by a tube 2|. Thepressure bafile may be filled with liquefied gas such as methylchloride, carbon dioxide, or oxygen. In this arrangement, the expendiblepart of the assembly comprises the pressure bot- 80 tle l9, the tube Itremaining on the gun. In operation, the aircraft crew may open the valve20 when protracted gun fire is anticipated, whereupon liquefied gasflows through the tube 2| into the tube I 6, where it vaporizes forcooling the gun, the vapor passing to the atmosphere through theopenings II. The valve 20 may be located in a position convenient foroperation by the aircraft crew.

While I have described my invention in detail 4 in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstandingmy invention, that various changes and modifications may bemade therein without departing from the spirit or scope thereof. I aimin the appended claims to cover all such modifications and changes.

I claim as my invention:

1. Means for cooling an aircraft machine gun comprising a demountableassembly including a perforate tube embracing the gun, an imperforatetube embracing the perforate tube, and a vaporable solid substancebetween said tubes for evaporation through the perforations of the firsttube in proximity to the gun barrel.

2. A cooling assembly for a gun barrel comprising a demountable assemblyincluding a perforate tube having clearance relation with the barrelexcept at its rearward end, an imperforate tube in annularly spacedrelation with the perforate tube, and a vaporable solid substancecontained within the annular space between said tubes adapted tovaporize and issue vapor through the inner tube perforations toward thegun barrel.

3. A replaceable cooling device for a gun having a barrel requiringcooling, comprising a pair of concentric tubes attached to one anotherat their ends and defining therebetween a space.

the inner tube being perforate and having clear ance relation with thegun barrel except at it rearward end whereat it fits the barrel close]:inward projections in the inner tube at its for ward end organized whenthe tube is slipped ove the barrel to engage the forward end thereo tohold the tube assembly in concentric relatim and to provide ventopenings between the pro jections and barrel, and a solid vaporable substance packed between the tubes in said spac adapted to issue vaporthrough the perforation of the inner tube toward the gun barrel tocooling the latter.

PETER F. ROSSMANN.

